It was found in ref. [1]} that there are both lower and
upper bounds on the value of \( x \) . The lower bound stems from measurements of
\( B_s - \overline{B_s} \)  mixing, which the \( Z^\prime \)  contributes to at
tree-level. The upper bound originates from measurements of the neutrino
trident cross-section, \( \sigma \mathopen {}\mathclose {\left(\nu _{\mu } N \rightarrow \nu _{\mu } N\mu ^+ \mu ^- \right)}\) , which also receives \( Z^\prime \)  contributions at
tree-level. We are left with the constraint \(0.04 < x < 0.67\)  [2]} which we will adhere to in this work. Substituting such values of \(x\)  into eq. REF 
implies that \(\theta _{sb}\)  is small. For small \(\theta _{sb}\) , the collider
phenomenology that we shall discuss is not sensitive to its precise value and
so should also be valid should the fit value of \(\mathcal {C}_9\)  change.
